Lost on Radar

Investigators determined that the pilot lost control of his MU-2 after pressing ahead in thunderstorms and severe icing conditions.

by Mark Lacagnina | May 17, 2019

The following information provides an awareness of problems that might be avoided in the future. The information is based on final reports by official investigative authorities on aircraft accidents and incidents.

Limited Experience in Type

Mitsubishi MU-2B-40. Destroyed. Four fatalities.

The pilot had begun training in the MU-2 about four months before he launched a flight with three passengers from Aguadilla, Puerto Rico, to Titusville, Florida, U.S., the morning of May 15, 2017. “Before beginning training in the airplane … the pilot had 21 hours of multiengine experience accumulated during sporadic flights over nine years,” said the report by the U.S. National Transportation Safety Board (NTSB). His total flight experience amounted to about 1,400 hours.

“Per a special federal aviation regulation, a pilot must complete specific ground and flight training, and log a minimum of 100 flight hours as pilot-in-command (PIC) in multiengine airplanes before acting as PIC of an MU-2B airplane,” the report said.

The pilot accumulated the requisite flight time quickly, mostly by conducting long cross-country flights accompanied by a flight instructor. “Although an MU-2B instructor described the pilot as a good, attentive student, it cannot be determined if his training was ingrained enough for him to effectively apply it in an operational environment without an instructor present,” the report said.

The pilot obtained a weather briefing about eight hours before departing from Aguadilla. Whether he checked the weather again before takeoff is unknown. During the flight, an air traffic controller broadcast information on the radio frequency the pilot was using about thunderstorms with tops to 44,000 ft along the route. Analysis of the weather conditions indicated that severe icing conditions likely were associated with the convective activity, the report said.

Shortly after leveling off for cruise flight at Flight Level (FL) 240 (approximately 24,000 ft), the pilot was cleared to fly directly to Titusville. “There is no evidence from the airplane’s radar track or the pilot’s communications with air traffic controllers that he recognized or attempted to avoid the convective conditions or exit icing conditions,” the report said. Recorded radar data showed that the MU-2 did not alter course or airspeed until radio and radar contact were lost about 2.5 hours after the pilot was cleared to fly directly to the destination.

The next day, debris from the airplane was found floating in a sheen of fuel on the surface of the Atlantic Ocean 32 mi (51 km) east of Eleuthera, Bahamas. “The U.S. Coast Guard conducted a search by air and sea for three days, but the airplane’s occupants were not found,” the report said.

Based on the findings of the investigation, NTSB concluded that the probable cause of the accident was “the pilot’s intentional flight into an area of known icing and convective thunderstorm activity, which resulted in a loss of control of the airplane.”

Jets

Cabin Pressure Anomalies

Boeing 737-300. No damage. No injuries.

Shortly after departing from Port Elizabeth, South Africa, the morning of May 8, 2018, the flight crew received a warning about the cabin pressurization system. Instead of climbing normally, cabin pressure had remained at 230 ft, the elevation of the departure airport; the rate of cabin pressurization change indicated zero; and the pressurization differential (the difference between cabin pressure and ambient pressure) had increased to the maximum of 8.3 psi. This indicated a cabin overpressurization.

“After some fault-finding, the crew decided to move the rotary switch for the pressurization system from the automatic (AUTO) mode to the standby (STBY) position,” said the report by the South African Civil Aviation Authority (CAA). “Immediately after the switch had been moved, the [cabin pressure] outflow valve began moving to the full open position, causing the cabin to depressurise while the aircraft was passing FL 230. … A muffled bang occurred, followed by the cabin fogging up.”

The commander selected the manual pressurization system control mode, and the outflow valve stopped moving when it was about halfway open. The outflow valve did not respond to any further inputs by the crew.

The pilots initiated a rapid descent to 10,000 ft, informed air traffic control (ATC) of the situation and requested and received clearance to return to Port Elizabeth. The 737 was landed without further incident, and none of the 116 passengers and eight crewmembers was injured.

“The pressurisation system on the Boeing 737-300 is controlled during all phases of flight by the cabin pressure control system (CPCS),” the report said. “Bleed air via the air-conditioning system is used to supply and distribute air in the cabin. By modulating the outflow valve, pressurisation can be accomplished.”

Investigators found that the CPCS had malfunctioned and was incapable of correctly modulating the outflow valve. Moreover, neither of the two pressure-relief valves had opened, as designed, to relieve cabin pressure when the pressurization differential reached 8.3 psi.

Fuel Controller Fails

Bombardier CRJ-200. No damage. No injuries.

The CRJ was climbing through 8,000 ft after departing from Johannesburg, South Africa, the morning of May 16, 2018, when it suddenly yawed left. “After carrying out troubleshooting, the flight deck crew identified the problem as an engine flameout,” said the report by the South African CAA. The pilots secured the left engine, declared an urgency and returned to Johannesburg, where the aircraft was landed without further incident. None of the 19 passengers and four crewmembers was injured.

Initial examination of the left engine revealed no visible damage. During further examination, the airline’s maintenance staff removed the fuel management unit (FMU) from the fuel pump and found excessive wear on the driveshaft. “The gear train on the FMU also displayed evidence of wear that had caused the drive gear to slip in operation,” the report said. “This disrupted the fuel supply to the engine, resulting in an engine shutdown.”

Struck by a Truck

Boeing 737-800. Substantial damage. No injuries.

Night visual meteorological conditions (VMC) prevailed as the 737 was being marshalled to its gate at Baltimore/Washington International Thurgood Marshall Airport on May 7, 2018. An airline maintenance vehicle also was being operated on the ramp. “The maintenance vehicle appeared to initially slow down for the airplane but then appeared to increase its speed to pass in front of the airplane before it could enter the gate,” the NTSB report said.

The maintenance vehicle struck the airplane, substantially damaging the nose landing gear doors and trunnion fittings, and the forward fuselage skin and stringers. None of the 179 people in the airplane or the truck driver was injured. NTSB concluded that the probable cause of the accident was “the maintenance truck driver’s failure to give way to the airplane.”

Corrosion Causes Flap Separations

Boeing 747-400F. Substantial damage. No injuries.

The 747 was nearing Miami during a cargo flight from Rio de Janeiro the night of May 17, 2010. “According to the operator, the flight crew heard and felt a large impact after 30-degree flaps were selected during the approach,” said the NTSB report. The crew was able to land the freighter without further incident.

An examination of the airplane revealed that a 12-ft (4-m) section of the inboard fore flap on the right wing had separated and struck the aft fuselage. The separated portion of the flap showed a large amount of corrosion on the lubrication fitting for the flap-attachment bearing. The report said that corrosion byproducts covered the lubrication fitting, preventing grease from reaching the bearing and causing the eventual failure of the flap attachment fitting.

A similar accident involving the same type of airplane had occurred during a cargo flight from Vienna to Frankfurt, Germany, the night of May 8, 2009. “Shortly after moving the flap lever [to select 30 degrees of flap], the crew heard the sound of a blow and noticed vibrations,” said the report by the German Federal Bureau of Aircraft Accident Investigation.

The 747-400F was landed without further incident. Damage was classified as severe, but none of the four crewmembers was injured. Examination of the freighter revealed that about 15 ft (5 m) of the inboard fore flap on the left wing had separated and struck the fuselage, puncturing a 10-ft (3-m) hole in the pressure vessel between the rear wing fairing and cargo door. Investigators determined that corrosion of the flap-attachment bearing had initiated a fatigue crack that eventually caused the failure of the flap attachment fitting.

Slippery When Damp

Boeing 737-800. No damage. No injuries.

Inbound from Sydney on a scheduled passenger flight, the flight crew listened to the automatic terminal information service (ATIS) broadcast before beginning the descent to Christchurch, New Zealand, the night of May 12, 2015. VMC prevailed at the airport with surface winds from 250 degrees at 12 kt, and Runway 29 was in use. This runway was seldom used, but Runway 20, which was nearly twice as long as Runway 29, was closed for construction, said the report by the Australian Transport Safety Bureau.

Later, however, an air traffic controller told the crew that the ATIS had changed. The controller advised that there were “quite a few changes from the previous; you want to have a listen.” The ATIS indicated that the surface winds had not changed substantially, but a light rain was falling, and Runway 29 was wet.

At the time, the first officer, the pilot flying, was coordinating with ATC about course deviations required to avoid convective activity in the arrival area. The captain was entering revised arrival and approach information into the flight management system and calculating landing performance for Runway 29, which was 1,703 m (5,588 ft) long. “Due to the higher-than-normal workload, the captain reported that they did not get the opportunity to listen [to the new ATIS information],” the report said.

However, the captain had heard the crew of another aircraft report that Runway 29 was damp. Expecting a damp runway, the captain nevertheless used dry-runway performance data in his calculations and found that landing distance available on Runway 29 would be sufficient for landing with an AUTOBRAKE 3 setting, which was the third-highest setting. (Although the airline previously had required pilots to consider a damp runway as a wet runway for landing performance calculations, it recently had changed the policy to treat a damp runway as a dry runway.)

On final approach, the pilot visually confirmed his impression that the runway was damp. “The aircraft landed within the required touchdown zone, using full reverse thrust [and] speed brakes, and the autobrake system engaged the wheel brakes,” the report said. “Recorded flight data showed that the aircraft initially achieved and at times exceeded the selected AUTOBRAKE 3 target deceleration rate.”

However, the report said that as the 737 crossed the midpoint of the runway, “the captain noted that there was a lot more surface water on [the latter] section of the runway than what was observed at the beginning of Runway 29.” Both pilots sensed that the aircraft was sliding; together, they applied manual wheel braking, overriding the autobrake system, and continued applying reverse thrust.

“The captain reported that when reverse thrust was stowed near the runway end, there was enough surface water on the runway to create a wall of spray,” the report said. “The first officer reported that the aircraft came ‘slowly sliding’ to a stop about 5 m [16 ft] from the runway end lights. The aircraft was then taxied to the terminal.”

The report noted that after the incident, the airline changed its policy again to require pilots to use wet-runway landing performance data when a runway is reported or expected to be damp.

Turboprops

Propeller Governor Leaks Oil

Bombardier Q400. Minor damage. No injuries.

The aircraft was descending through 12,000 ft to land at Manchester, England, the morning of May 26, 2017, when the flight crew received an indication of low oil pressure in the right engine. The gauge showed that oil pressure was decreasing steadily, so the crew shut down the engine.

The pilots subsequently conducted a single-engine instrument landing system (ILS) approach to Manchester Airport and landed the Q400 without further incident. None of the 53 passengers and four crewmembers was injured.

“It was found that a valve cap on the overspeed governor test solenoid had detached, allowing most of the oil from the no. 2 engine lubrication system to be lost,” said the report by the U.K. Air Accidents Investigation Branch (AAIB). “Investigation of the component revealed that the four cap securing bolts had failed, predominantly in fatigue.”

The reason that the four bolts failed could not be determined conclusively, “but the possibility that a lower-than-specified torque tightening figure was used on one or more bolts during assembly could not be ruled out,” the report said.

‘Improper Crosswind Technique’

ATR 72-600. Substantial damage. No injuries.

Before leaving Delhi, India, the afternoon of May 5, 2016, the flight crew had extra fuel added to the aircraft due to weather conditions at the destination, Indore. Nearing Indore, the crew learned that the airport had surface winds from 130 degrees at 8 kt and thunderstorms with bases at 3,000 ft.

The ATR was on final approach during a VHF omnidirectional radio (VOR) approach to Runway 07 when the crew asked ATC for an update on wind conditions. When told that the winds were from 320 degrees at 12 kt, they discontinued the VOR approach and requested, and received clearance, to conduct the ILS approach to Runway 25.

When the aircraft intercepted the ILS localizer course, the crew was cleared to land on Runway 25 and was told by ATC of moderate rainfall at the airport. “As the aircraft descended through 600 feet, the autopilot was disconnected,” said the report by a committee of inquiry established by India’s Ministry of Civil Aviation. “After the aircraft touched down, it veered to the right. The PIC tried to control the aircraft using rudder to turn it to the left. However, the aircraft went excessively to the left.”

Despite application of full right rudder, the ATR veered off the left side of the runway onto rough terrain. Damage was substantial, but none of the 70 occupants of the aircraft was hurt.

The report said that the probable causes of the accident were “improper crosswind landing technique and failure to use nosewheel steering or differential braking after rudder efficiency was diminished due to decreasing speed.” The poor condition of the runway was cited as a contributing factor.

Piston Airplanes

Waited Too Long to Feather

Cessna 310F. Destroyed. One fatality, one serious injury.

The commercial pilot and a designated pilot examiner departed from North Little Rock (Arkansas, U.S.) Municipal Airport for a check ride the afternoon of May 5, 2016. The left engine lost partial power on initial climb, and the pilot decided not to secure the engine because it was still producing “positive thrust.” He told investigators that the examiner agreed with the decision.

The pilot then made left turns to remain in the traffic pattern and return to the runway. Due to the asymmetric thrust, “the left turns, toward the partially running left engine, would have decreased directional control of the airplane,” the NTSB report said. “While on the downwind leg of the traffic pattern, the left engine lost further power, and the pilot attempted to feather the left propeller. Although he moved the left propeller control full aft, the propeller did not feather.”

The 310 had reached a maximum height of 255 ft as airspeed decreased below the minimum single-engine best rate of climb speed. “As it turned toward the airport, the airplane collided with terrain in a 45-degree left bank and slight nose-down pitch attitude and was subsequently destroyed by a post-crash fire,” the report said. The examiner was killed, and the pilot sustained serious injuries.

The cause of the power loss could not be determined because of the extent of the damage. However, investigators determined that the pilot likely was unable to feather the left propeller because the rpm had decreased to the point at which the start locks engage. “The start locks engage to prevent feathering of the blades during engine shutdown on the ground,” the report said. “In the event of an in-flight engine shutdown, the propeller must be feathered before [propeller] speed decays to 800 rpm.”

NTSB determined that the probable causes of the accident were “the pilot’s failure to promptly feather the left propeller upon the initial loss of engine power shortly after takeoff and his failure to maintain airspeed while maneuvering with one engine inoperative.”

One-Hundred-Mile Overflight

Piper Chieftain. Destroyed. One fatality.

VMC prevailed when the pilot departed under visual flight rules from Quebec City for a one-hour cargo flight to Saint Hubert the night of May 3, 2017. Shortly after takeoff, the pilot was cleared by ATC to fly directly to the destination at 2,000 ft. The pilot’s acknowledgement of the clearance was his last radio contact with ATC.

“The airplane continued flying past the destination airport in straight-and-level flight at 2,100 ft, consistent with the airplane operating under autopilot control, until it was about 100 miles [161 km] beyond the destination airport,” the NTSB report said. The Chieftain was in a 45-degree left bank when it struck terrain near Colton, New York, U.S.

Investigators determined that the pilot likely had become incapacitated and that the airplane had continued flying on autopilot until the fuel in the selected tanks was exhausted. An autopsy revealed that the pilot had used marijuana at some point before the flight, but the cause of his incapacitation could not be determined conclusively, the report said.

Helicopters

‘Challenging’ Weather Conditions

Bell 206B3. Destroyed. One fatality.

The pilot departed from Husthwaite, England, to fly the JetRanger to Walton Wood for its annual maintenance inspection the afternoon of May 30, 2018. “This was a route the pilot had flown many times,” the AAIB report said. However, for this flight, “the weather conditions en route were challenging.” The forecast called for visibilities as low as 3,000 m (about 2 mi) and ceilings between 300 and 700 ft.

Several witnesses near Aldborough saw the helicopter flying apparently normally before it suddenly pitched nose-up and climbed steeply into the clouds. “It was then seen to emerge from the cloud, rotate through 540 degrees, then descend rapidly, striking the ground in an approximately level attitude,” the report said. “The helicopter became inverted and caught fire. The pilot was fatally injured.”

Investigators determined that the pilot likely became distracted by the adverse weather conditions during the flight. “Having entered cloud, it is likely that the pilot became spatially disoriented and was unable to maintain control of the helicopter,” the report said. “Having exited the cloud, with a low cloud base, it is likely the pilot did not have sufficient time to regain control before impact with the ground.”

The report noted that the pilot had limited recent experience — he had flown only twice in the preceding nine months — but may have felt the need to complete the flight despite the adverse weather conditions because the annual inspection was due the next day.

Overweight S76 Strikes Power Lines

Sikorsky S76C. Substantial damage. No injuries.

The flight crew departed from a temporary landing area in Latur, India, to fly four government officials to Mumbai the morning of May 25, 2017. “The helicopter lifted into hover and turned approximately 90 degrees to its left to initiate takeoff into the winds,” said the report by the commission of inquiry. “The PIC commenced a slow vertical lift-off, and the helicopter hovered out of ground effect at about 25 feet and thereafter gained height to [approximately] 39 feet.”

When the pilot attempted to transition from the hover to forward flight, rotor speed began to decrease and the S76 began to descend. The pilot retracted the landing gear and pitched the helicopter nose-up in attempt to clear power lines. However, the lower fuselage struck the power lines, and the pilot lost yaw control. The helicopter turned right, and the main rotor blades struck a tree and the roof of a truck. “The tail rotor blades also hit the roof of a hut and sheared off,” the report said. “Thereafter, the helicopter crash-landed and settled on the ground between the truck and the hut. All six occupants escaped the helicopter safely with no injuries.”

The report said that the crew did not use the actual weights of the passengers and their baggage in calculating the S76’s takeoff weight and balance. Their calculations showed a takeoff weight of 10,891 lb (4,940 kg). Investigators determined that the actual takeoff weight was close to the maximum of 11,400 lb (5,171 kg), which required a takeoff distance that was longer than that available at the temporary airstrip.

The committee of inquiry concluded that among the probable causes of the accident was the “attempted takeoff at an AUW [all-up weight] higher than the permissible limit for the prevailing conditions at the time of takeoff.” A contributing factor was the PIC’s “wrong technique for departure from a congested, hostile area.”

Preliminary Reports, March 2019

Date

Location

Aircraft Type

Aircraft Damage

Injuries

This information, gathered from various government and media sources, is subject to change as the investigations of the accidents and incidents are completed.

March 1

London

Airbus A320-214

substantial

8 minor, 167 none

The flight crew rejected a takeoff at low speed after the left engine failed. Eight passengers sustained minor injuries during the evacuation.

March 3

Union Center, South Dakota, U.S.

Bell 407

substantial

1 minor, 2 none

Night visual meteorological conditions (VMC) prevailed when the emergency medical services helicopter was landed to pick up a patient. A paramedic who had exited the 407 sustained minor injuries when the main rotor blades struck the top of an ambulance that was being driven toward the helicopter.

March 4

Little Grand Rapids, Manitoba, Canada

Cessna 208B

substantial

1 minor, 6 none

The pilot sustained minor injuries when the Caravan struck the frozen surface of a lake on approach to the airport.

March 4

Presque Isle, Maine, U.S.

Embraer 145XR

substantial

3 minor, 28 none

Visibility was 1/2 mi (800 m) in snow and freezing rain when the flight crew rejected the first approach to Runway 01. On the second approach, the airplane was landed between the runway and the parallel taxiway. Two passengers and one crewmember sustained minor injuries.

March 5

Talking Rock, Georgia, U.S.

Hughes 500

substantial

1 fatal

The pilot was using an aerial saw to trim trees along power lines when the helicopter entered a spin and struck terrain.

March 8

Pahokee, Florida, U.S.

Piper Aztec

destroyed

5 fatal

VMC prevailed when the pilot reported that he was shutting down the rough-running left engine and diverting to Pahokee. Witnesses saw the Aztec in a rapid left-wing-low descent before it struck a lake near the airport.

March 8

Forks, Washington, U.S.

Bell UH-1B

substantial

1 fatal

The helicopter struck mountainous terrain shortly after taking off to conduct an external-load operation at a nearby logging site.

March 9

San Martín, Colombia

Douglas DC-3

destroyed

14 fatal

The DC-3 was climbing through 8,100 ft during a charter flight when the flight crew reported engine problems and said that they were diverting to an airstrip in San Martín. The aircraft struck terrain shortly after the crew reported the airstrip in sight.

March 9

Chamblee, Georgia, U.S.

Gulfstream IV

substantial

14 none

Nearing Atlanta’s DeKalb-Peachtree Airport, the flight crew was told that Runway 34, which was 3,967 ft (1,210 m) long, was in use and that Runway 03R/21L, which was 6,001 ft (1,829 m) long, would be available in 20 minutes. The crew initially replied that they would hold until the longer runway was available but then said that they would be able to land on Runway 34. The G-IV touched down hard on landing, and a post-flight examination revealed substantial damage to the fuselage.

March 9

Longview, Texas, U.S.

Cessna T337C

destroyed

4 fatal

The Skymaster struck terrain about an hour after departing from Lancaster, Texas, for a visual flight rules flight to New Orleans.

March 10

Addis Ababa, Ethiopia

Boeing 737 MAX 8

destroyed

157 fatal

The aircraft struck terrain shortly after the flight crew reported flight control problems on departure and said that they were returning to the airport.

March 10

San Pedro Peralta, Mexico

Hawker Siddeley 125-600A

destroyed

1 fatal, 1 serious

A load of cocaine reportedly was found in the Hawker after a forced landing in the jungle.

March 10

Galliano, Louisiana, U.S.

Bell 407

destroyed

2 fatal

The helicopter struck terrain shortly after taking off to transport a passenger to an offshore platform.

March 10

Charlotte, North Carolina, U.S.

Bombardier CRJ900, CRJ700

substantial

none

The CRJ900 was being pushed back from a gate when its horizontal stabilizer struck the horizontal stabilizer on the parked CRJ700.

March 12

Madeira, Ohio, U.S.

Piper Chieftain

substantial

1 fatal

The pilot was conducting a survey flight when he reported a fuel problem and said that he was diverting to Cincinnati Municipal Airport. Witnesses saw the Chieftain flying very low and heard unusual engine sounds before the airplane struck terrain about 5 nm (9 km) from the airport.

March 13

St. Petersburg, Florida, U.S.

Beech E55 Baron

substantial

2 none

The pilot said that he became distracted and neglected to lower the landing gear. The gear-warning horn failed to activate before the Baron touched down and slid on its belly.

March 13

Keene, New Hampshire, U.S.

Hughes TH-55

substantial

1 none

The helicopter was nearing the airport when the pilot heard a loud thud and the upper right portion of the canopy shattered. Debris struck and damaged the main rotor blades.

March 16

Riverside, California, U.S.

Beech 50 Twin Bonanza

substantial

1 fatal

The pilot reported electrical system and engine problems on departure from Chino, and was diverting to Riverside when the Twin Bonanza crashed in a residential area.

March 17

Plain City, Ohio, U.S.

Cessna 421B

destroyed

1 fatal

The 421 was nearing the destination, Delaware Airport, when the pilot reported that he was encountering icing conditions. Shortly thereafter, the 421 struck a utility pole and crashed on snow-covered terrain 8 mi (13 km) from the airport.

March 18

Kuala Lumpur, Malaysia

Bombardier Challenger 300

substantial

1 fatal

The Challenger’s left wing struck an airport engineering vehicle while landing. The vehicle driver was killed.

March 18

Yukon, Oklahoma, U.S.

IAI Westwind

destroyed

2 fatal

The Westwind was on short final approach when it rolled inverted and struck terrain. Initial examination of the wreckage revealed that the left thrust reverser was unlatched and open, and the right thrust reverser was closed and latched.

March 19

Tehran, Iran

Fokker 100

substantial

33 none

The flight crew could not extend the landing gear due to hydraulic system problems. After unsuccessfully trying the emergency gear-extension procedure, the pilots landed the Fokker with the gear retracted.

March 20

Madill, Oklahoma, U.S.

Robinson R22

substantial

1 none

Shortly after takeoff, the clutch warning light illuminated. The pilot heard a bang and felt the R22 shudder. He then conducted an autorotational landing on rough terrain, and the helicopter rolled over. Initial examination of the R22 revealed that both rotor belts were missing.

March 23

Matsieng, Botswana

Beech King Air B200

destroyed

1 fatal

The pilot made several low passes over an airport clubhouse located near the airport traffic control tower. The facilities were evacuated before the King Air struck both of them and several parked vehicles.

March 24

Fort Lauderdale, Florida, U.S.

Pilatus PC-12

substantial

3 none

The PC-12 was climbing through 20,000 ft when the pilot heard a loud bang. The left side of the windshield shattered but remained attached. He returned to Fort Lauderdale and landed the airplane without further incident. Investigators found the windshield seal torn, the bottom and upper left corners of the windshield pushed outward and the lower left heating element burned.